That big physics announcement explained

Physicists have found a long-predicted twist in light from the Big Bang that represents the first image of ripples in the universe called gravitational waves, researchers announced today. The finding is direct proof of the theory of inflation, the idea that the universe expanded extremely quickly in the first fraction of a second after it was born. What’s more, the signal is coming through much more strongly than expected, ruling out a large class of inflation models and potentially pointing the way toward new theories of physics, experts say.

And why should we care?

The timing of inflation, in turn, tells physicists about the energy scale of the universe when inflation was going on. BICEP2’s value of r suggests that this was the same energy scale at which all the forces of nature except for gravity (the electromagnetic, strong and weak forces) might have been unified into a single force—an idea called grand unified theory. The finding bolsters the idea of grand unification and rules out a number of inflation models that do not feature such an energy scale. “This really collapses the space of plausible inflationary models by a huge amount,” Kamionkowski says. “Instead of looking for a needle in a haystack, we’ll be looking for a needle in a bucket of sand.” Grand unified theories suggest the existence of new fields that act similarly to the Higgs field associated with the Higgs boson particle discovered in 2012. These new fields, in turn, would indicate that other, heavier Higgs boson particles also exist, although with masses so high they would be impossible to create in any traditional particle accelerator. “This measurement is allowing us to use the early universe as a lab for new physics in energy ranges that are otherwise inaccessible to us,” Kamionkowski says.

Yeah, gravity waves and gravitational waves are two entirely different things.

Gravity waves form when material things get lifted up, then are pulled back down by gravity. A wave of the thing goes rippling out through the thing, just like a wave in the ocean … which is a gravity wave. Wind waves, tidal waves, the ripples from a thrown pebble, all require gravity pulling back down on the initial lift. There are gravity waves deep under water, and in the atmosphere as well, where two different densities meet, which is why the term exists.

But those waves don’t cause changes in the gravitational pull, so they aren’t gravitational waves. Well, maybe they cause minute changes—they should, as all matter has gravitational pull–but it can’t be measured. The amount of material sloshing about is just too small.

There are possibly-detectable waves in gravity from the very dense masses of neutron stars in close orbit around each other. Einstein says that swirling humongity should cause ripples of the very force of gravity, which are gravitational waves. That is, waves of gravitation.

Anyhow, that’s getting ‘way out of my league. Gravity waves I have seen and surfed. Gravitational waves are theoretical physics, up to now.

If this discovery holds up, there is not only insight into the beginning of the universe, but another confirmation of Einstein. He predicted gravitational waves.

(The best way to detect gravitational waves looked to be something like floating an astronaut next to a binary neutron star with a dumbbell in each hand, and asking her if they were shaking. The instrument version was going to at least be floating far from Earth, and be damned sensitive.)

I had learned that the hypothetical Grand Unifed Theory would include quantum gravity, which is why it’s been so elusive — and that the fundamental forces other than gravity had already been unified. Did I learn it incorrectly?

I had learned that the hypothetical Grand Unifed Theory would include quantum gravity, which is why it’s been so elusive — and that the fundamental forces other than gravity had already been unified. Did I learn it incorrectly?

They’ve shown that they very well could be unified, and they’ve shown pretty well how that would work in detail (lots of details, really, depending on which GUT you’re talking about, since at this point there’s no such thing as “the GUT”). But now let me quote wiki:

Because their masses are predicted to be just a few orders of magnitude below the Planck scale, at the GUT scale, well beyond the reach of foreseen particle colliders experiments, novel particles predicted by GUT models cannot be observed directly. Instead, effects of grand unification might be detected through indirect observations such as proton decay, electric dipole moments of elementary particles, or the properties of neutrinos.[1] Some grand unified theories predict the existence of magnetic monopoles.

So, no, still no evidence. Those are predictions of potential evidence, which is useful, but nothing substantial so far….

As of 2012, all GUT models which aim to be completely realistic are quite complicated, even compared to the Standard Model, because they need to introduce additional fields and interactions, or even additional dimensions of space. The main reason for this complexity lies in the difficulty of reproducing the observed fermion masses and mixing angles. Due to this difficulty, and due to the lack of any observed effect of grand unification so far, there is no generally accepted GUT model.

The way I read “lack of any observed effect,” I take it that there is no observed effect, which is not what one would expect if we already had a verified theory to work with.

Physicist Pharyngulites, I was an above-average student in math and physics in high school (and languages :P ), but I have forgotten most of my math skills because of working most of my life in the publishing professions. Can one (or more) of you list the math subjects (and in what order) I need to study to be able to UNDERSTAND all of this extremely interesting stuff?? I would greatly appreciate this. An (ordered) list of books to study would do nicely. Thank you…

(How much would that pile of books set me back?) I have time on my side.

S.W. Hawking and G.F.R. Ellis, The Large Scale Structure of Space-Time, Cambridge University Press, 1973.

Certainly out of date in some ways, but an excellent grounding in General Relativity. The authors claim that the reader only needs simple calculus, algebra, and point-set topology, as they supply a lot of the basics. That might be is definitely* optimistic, and it is a slog (have lots of paper and pencils handy), but patience, perseverance and occasional heavy drinking may see you through.

Your best bet might be to enroll in an online course. This sort of thing. They probably cover the prerequisites as well.

*I just flipped through some of it for the first time in years. Yikes.

Before doing a press release, the team which made the discovery paid a visit to the grandfather of inflationary theory, Andrei Linde, and told him of their results. They took a video of it, the unveiling of the vindication of 30+ years of work: https://www.youtube.com/watch?v=ZlfIVEy_YOA&feature=youtu.be . It is without a doubt one of the most powerful things I’ve ever seen.